A metal core substrate is obtained as a result of outline shaping performed on a substrate including a core plate and an insulating layer provided on each of two surfaces of the core plate. An outer circumferential edge of the metal core substrate has an insulating structural portion, which includes an end surface of the core plate that is retracted from an end surface of the outer circumferential edge of the metal core substrate and an insulating covering portion covers the end surface of the core plate. Separation portions to be filled with the resin and coupling portions which are to be removed before outline shaping are formed at outline shaping positions of the core plate. At the time of outline shaping, only the resin is present at the outline shaping positions.